Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

While this finding is perhaps not surprising, the marked differences in children at about age 10 may explain some of the great health disparities between U.S. adults of these races, the researchers said. These disparities have been widely studied in teens but this study shows these health differences are already present among younger children.

"The research community has already provided a lot of evidence that there are significant differences across the life course in health indicators among black, Latino and white people in general," said Dr. Mark Schuster, chief of general pediatrics at Boston Children's Hospital and lead author of the study. "But I was struck by the consistency of disparities across so many health indicators."

The researchers found that a child's school, and parents' education and income strongly related to a child's health. Children who went to better schools and had parents with a higher income and more education were healthier, no matter what their race or ethnicity. But white children were more likely to have these advantages.

The study of differences among fifth graders in three U.S. cities is the largest, most detailed research on these health disparities, experts said.

"What I think makes this research stand out is the young age of the children examined," said Rebecca London, a senior researcher of youth health at Stanford University in California, who was not involved in the research. "The findings are important because they document the extent of the problem for children as young as 10 and 11 years old."

The study involved 5,119 fifth graders in public school who were chosen at random from three metropolitan areas — Birmingham, Ala.; Houston; and Los Angeles. Researchers interviewed the children and their parents, and assessed factors ranging from seat-belt use, exercise and obesity, to substance abuse and witnessing of violence.

"Some of the numbers in the paper are very striking," London said. "Especially where the children have witnessed violence." One in five black children and one in 10 Latino children had witnessed a threat or injury from a gun, compared with one in 20 white children in these cities.

Black children were also more likely than either Latino or white children to smoke and drink alcohol.

While one in six white children in the study were obese, one in three black or Latino children were obese. Black and Latino children were also less likely to report vigorous exercise, compared with their white counterparts.

Overall, black and Latino children were more likely to say they had an overall poor state of health.

While important, the results don't necessarily represent the U.S. as a whole, London said. "It would be important to document these same findings in other geographic areas," she said, especially to help researchers better understand why the gap in health disparities is reduced much more among Latino children than black children from households with higher incomes.

While the findings suggest that interventions aimed at improving children's health should likely start earlier to prevent some of the disparities, many of the problems identified are due to complex social dynamics, Schuster said.

"More work is needed to identify what is causing these disparities, so that we can find ways to improve all children's health," he said.

London said that economic support, violence prevention, improved school nutrition, parent education on health, general promotion of education and health insurance are just a few of the support programs to boost health of children.

One important avenue for positive influence appears to be schools. "The results point to the potential for schools to intervene to promote healthy behaviors and safe environments during and outside the school day," London said.

Collaborative efforts between the health workers and educators could lead to a better understanding of the reasons for the disparities, and identify potential solutions, she said.

The study is published tomorrow (Aug. 23) in the New England Journal of Medicine.